Non aqueous personal care compositions can typically contain major amounts of a non-aqueous carrier which provides a suitable matrix into which the active ingredients, such as personal care actives or pharmaceutical actives, and other functional ingredients, are added to form personal care products that are usually pasty in appearance. It is known in the art that the non-aqueous carrier can be composed of a blend of liquid component(s) and solid component(s) to provide a stable suspension during the formulation of said personal care compositions. For example, the typical liquid components in a essentially non-aqueous personal care composition are polyethylene glycol polymers of low molecular weight, typically in the range of 200-400. The solid component which is usually added to modify the rheology of the composition can be a higher molecular weight polyethylene glycol of molecular weights between 1,000-10,000. Such mixtures of a liquid polyethylene glycol and a solid polyethylene glycol have the consistency of an ointment. In addition, liquid polyethylene glycols are excellent solvents for a variety of flavor oils and pharmaceutical actives. Furthermore, such blends allow the flexibility of formulating actives and other functional ingredients that are water-sensitive, in a non-aqueous medium, while at the same time, possess good solubility in water. These blends are therefore suitable as bases for ointment formulations. For purposes of designing a suitable non-aqueous medium with liquid polyethylene glycols, liquid polyethylene glycols are combined with another additives of a specific molecular weight, in a select ratio to achieve the appropriate consistency. The choice of the additive is limited to solid polyethylene glycols of molecular weights typically ranging from about 1000 to about 10000. The function of the solid polyethylene glycol is limited to providing adequate rheology or the desired consistency to the composition. Many personal care compositions can contain additional functional ingredients that provide specific benefits to a composition such as foam boosting, defoaming, emulsification, detergency, suspending, wetting, dispersing, irritation mitigation, solubilizing, and lubrication. Examples of such ingredients are the nonionic triblock copolymers of ethylene oxide and propylene oxide which are available in a wide range of molecular weights and in various proportions of ethylene oxide and propylene oxide. Applicants have observed that in the design of a non-aqueous medium such as the one stated above, if the solid polyethylene glycol were to be replaced with a solid nonionic triblock surfactant comprising ethylene oxide and propylene oxide, the resulting non-aqueous blend is not very stable above moderately ambient temperatures. These blends tend to liquefy and lose a substantial portion of their viscosity at moderately ambient temperatures or split in to two phases at ambient temperatures. Personal care compositions or pharmaceutical compositions comprising such a carrier are subject to separation of the active ingredients due to the loss of viscosity or suspending ability of the carrier. This could lead to an overdose or underdose of active ingredients with potentially serious consequences.
Further, personal care products, such as mouthwashes, cosmetic creams, gels and lotions, antiperspirants, deodorants, and over-the-counter medicaments such as salves and ointments, which are formulated comprising a non-aqueous blend, are subject to freeze-thaw cycles during shipment and storage. Subjecting such personal care products to several freeze thaw cycles can alter the rheology of the product, creating a product dispensing problem when the product becomes too hard or too soft or too viscous, and hence, difficult to use. Thus, there is a need for a non-aqueous carrier which offers a wide formulation flexibility and has the ability to withstand the extremes of transportation temperatures without significantly altering the rheology and the integrity of the composition.
The art is replete with non-aqueous carrier blend formulations. Specifically, WO 95/01155, discloses the use of a non-ionic surfactant as a stabilizing agent in antibody containing oral compositions at levels of 0.01-6% by weight of the oral composition. Preferred non-ionic surfactants are the solid EO/PO/EO triblock copolymers known as PLURONIC.RTM. F 68, F 88 and F 108. U.S. Pat. No. 5,374,368 describes the use of liquid EO/PO/EO triblock co-polymers (PLURONIC.RTM. L 31 and L 35) in stable hydrogen peroxide releasing dental care compositions at levels of 55-90% by weight of the dental care composition. U.S. Pat. No. 3,740,421 discloses gel forming solid EO/PO/EO triblock copolymers useful in cosmetic and personal care formulations at levels of approximately 20-25% by weight. Preferred solid EO/PO/EO triblock copolymers have a molecular weight of 4,600-16,000. Said solid EO/PO/EO triblock copolymers form a gel when added to an aqueous solution. U.S. Pat. No. 3,867,533 discloses aqueous gel compositions containing solid EO/PO/EO triblock copolymers, having a molecular weight of 6,450-20,000 useful at levels of approximately 20% by weight. Said compositions are useful in preparing cosmetic formulations. U.S. Pat. No. 3,997,458 discloses solid triblock co-polymers of EO/PO/EO useful in wound cleansing compositions at levels of approximately 10% by weight. Said EO/PO/EO copolymers have a molecular weight of 5,000-13,500 (e.g., PLURONIC.RTM. F 98, F 108 - available from BASF Corporation, Mt. Olive, N.J.). U.S. Pat. No. 4,382,078 discloses water based aerosol compositions containing a dimethylether propellant and solid EO/PO/EO triblock copolymers at levels of 1-6% by weight. U.S. Pat. No. 4,465,663 discloses clear aqueous cosmetic gels containing solid EO/BO(butylene oxide)/EO triblock copolymers at levels of approximately 20%. U.S. Pat. No. 5,035,880 discloses a stable dentrifice compositions containing a cetylpyridinium bactericide and EO/PO/EO solid triblock copolymers (PLURONIC.RTM. F 127), and polyethylene glycol at levels of 15-80% by weight. U.S. Pat. No. 4,476,107 discloses a mouthwash containing EO/BO(butylene oxide)/EO triblock copolymers at levels of 0.5-5.0% by weight. U.S. Pat. No. 5,057,307 discloses oral hygiene gels containing non-ionic surfactants, coating substances; and viscosifiers. Said non-ionic surfactants are PLURONIC.RTM. F 108 and F 127 available from BASF Corporation, Mt. Olive, N.J. U.S. Pat. No. 5,256,396 discloses a topical composition comprising an EO/PO/EO solid triblock copolymer (PLURONIC.RTM. F 127) used at a level of more than 10% to about 17% by weight. EPO-546-627A discloses mouthwash compositions comprising solid EO/PO/EO triblock copolymers such as PLURONIC.RTM. 108, 88 at levels of 0.5-3% by weight. EP 0-551-626 discloses a thermoreversible pharmaceutical gel comprising solid EO/PO/EO triblock copolymer such as PLURONIC.RTM. F 127 at a level of 10 to 30% by weight. U.S. Pat. No. 5,073,368 discloses mouthwashes containing solid EO/PO/EO triblock copolymers such as PLURONIC.RTM. F 87 at levels of 0.1-3% by weight. WO 93113750 discloses an ocular cleansing composition comprising solid PLURONIC.RTM. P 85 and paste PLURONIC.RTM. F 87 EO/PO/EO triblock copolymers. PLURONIC.RTM. P 85 is 4-9% by weight of the cleansing composition, PLURONIC.RTM. F 87 is 0.5-2% by weight of the cleansing composition. U.S. Pat. No. 5,096,698 discloses a dental creme composition containing a non-ionic triblock liquid EO/PO/EO copolymer or a solid triblock EO/PO/EO copolymer at levels of 0.1-5% by weight. Said copolymers help to prevent phase separation. PLURONIC.RTM. F 108 (solid) is most preferred, followed by PLURONIC.RTM. F 87, PLURONIC.RTM. F 127, and PLURONIC.RTM. L 72. Liquid and solid PLURONIC.RTM. surfactants are not used together in said dental creme composition. Finally, U.S. Pat. No. 5,709,852 discloses a nonaqueous carrier for personal care compositions comprising: (a) nonionic liquid triblock EO/PO/EO copolymer and (b) nonionic solid triblock EO/PO/EO copolymer.
However, the art does not disclose a blend of a liquid polyoxyalkylene compound and a solid ethylene oxide/propylene oxide/ethylene oxide (EO/PO/EO) triblock copolymers, as stable non-aqueous carrier blends for personal care compositions. Applicants have surprisingly discovered that blends of a liquid polyoxyalkylene compound and solid EO/PO/EO triblock copolymers significantly improve the rheological consistency, maintain freeze/thaw stability and provide adequate thermal stability for personal care products.